Add 'ENV' to the list of runtime elements that may be exported. (#6855)

Adding environment variables is inconvenient for MODULARIZE=1 builds without exporting the ENV object.

AUTHORS

@@ -351,3 +351,4 @@ a license to everyone to use it as detailed in LICENSE.)
 * Alexander Bich <quyse0@gmail.com>
 * Ashleigh Thomas <ashleighbcthomas@gmail.com>
 * Veniamin Petrenko <bjpbjpbjp10@gmail.com>
+* Ian Henderson <ian@ianhenderson.org>

src/modules.js

@@ -376,6 +376,7 @@ function exportRuntime() {
     'writeAsciiToMemory',
     'addRunDependency',
     'removeRunDependency',
+    'ENV',
     'FS',
     'FS_createFolder',
     'FS_createPath',